The institute of electrical and electronics engineers (IEEE) 802.16e standard was adopted in 2007 as a sixth standard for international mobile telecommunication (IMT)-2000 in the name of ‘WMAN-OFDMA TDD’ by the ITU-radio communication sector (ITU-R) which is one of sectors of the international telecommunication union (ITU). An IMT-advanced system has been prepared by the ITU-R as a next generation (i.e., 4th generation) mobile communication standard following the IMT-2000. It was determined by the IEEE 802.16 working group (WG) to conduct the 802.16m project for the purpose of creating an amendment standard of the existing IEEE 802.16e as a standard for the IMT-advanced system. As can be seen in the purpose above, the 802.16m standard has two aspects, that is, continuity from the past (i.e., the amendment of the existing 802.16e standard) and continuity to the future (i.e., the standard for the next generation IMT-advanced system). Therefore, the 802.16m standard needs to satisfy all requirements for the IMT-advanced system while maintaining compatibility with a mobile WiMAX system conforming to the 802.16e standard.
A control channel can be used for transmission of various type of control signal for communication between a base station and a mobile station. Examples of the uplink control channel are various such as a fast feedback channel, a hybrid automatic repeat request (HARM) feedback channel, a sounding channel, a ranging channel, a bandwidth request channel, etc.
The ranging channel can be used for uplink synchronization. The ranging channel can be classified into a non-synchronized ranging channel (NS-RCH) and a synchronized ranging channel (S-RCH). The NS-RCH can be used for initial access and handover. A mobile station shall not transmit any other uplink burst or uplink control channel signal in the AAI subframe where it transmits a ranging signal by using the NS-RCH. The S-RCH can be used for periodic ranging.
Meanwhile, an IEEE 802.16m system can support not only an MS supporting the IEEE 802.16m system, but also an MS supporting an IEEE 802.16e system because it has backward compatibility. A case in which the IEEE 802.16m system supports the 802.16e mobile station can be referred to as a legacy support mode.
Resource allocation method for a ranging channel in legacy support mode is required.